Radtechwxman Posted April 22, 2016 Share Posted April 22, 2016 Full sampling won't be till Mon. 0z runs Sun may have a partial sampling Link to comment Share on other sites More sharing options...
OUGrad05 Posted April 23, 2016 Share Posted April 23, 2016 Has the storm for Tuesday been sampled yet in the Upper Air Network? Just wondering... Don't think so Link to comment Share on other sites More sharing options...
OKpowdah Posted April 23, 2016 Share Posted April 23, 2016 Guys, FYI, there's really nothing that shows a sudden increase in skill when a trough in question comes onshore. The discussion of sampling really doesn't have much significance Link to comment Share on other sites More sharing options...
Jim Martin Posted April 23, 2016 Share Posted April 23, 2016 Ah. Did not know that... Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 The noticeable VBV in the 18Z GFS at 00Z-- mainly in KS-- would be kind of concerning for storm mode. From 18Z GFS at 7pm tuesday @ICT. One thing I did find cool with this sounding was the SARS having both the 7pm OUN 1999/5/3 sounding, and ICT 8pm 1999/5/3 sounding. Link to comment Share on other sites More sharing options...
SnowWeenie Posted April 23, 2016 Share Posted April 23, 2016 I am almost always a lurker but I wanted to comment about the false notion that there is a dramatic change once the trough comes ashore. It has been discussed many times in the Mid-Atlantic forum but to recap DTK's statement on this topic is that both the North and Southern Hemisphere have very similar model verification even though the southern hemisphere has less upper air samplings and observations in general. So I wouldn't expect a sudden increase in skill on Monday. Link to comment Share on other sites More sharing options...
andyhb Posted April 23, 2016 Share Posted April 23, 2016 The noticeable VBV in the 18Z GFS at 00Z-- mainly in KS-- would be kind of concerning for storm mode. The trough is getting too amplified on this run of the GFS (also to do with the ridge out ahead shortening the wavelengths) and encouraging more meridional flow at 500 mb. The Euro and CMC (and the UKmet from what I've seen of it) do not have this as an issue. Note that the bulk shear values are pretty unimpressive too. The Euro had 50-65 kts of 0-6 km shear across the dryline in OK at 00z, whereas the 12z/18z GFS barely had/has 40 kts. Probably worth noting that the GFS' 500 mb mid-range verification recently has been pretty abysmal (Sam AKA OKpowdah was mentioning earlier on Twitter that the CMC even has been outperforming it in this department). Something closer to the Euro or especially the CMC at 500 mb has higher end risk written all over it for pretty much the length of the dryline. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 23, 2016 Share Posted April 23, 2016 The noticeable VBV in the 18Z GFS at 00Z-- mainly in KS-- would be kind of concerning for storm mode. From 18Z GFS at 7pm tuesday @ICT. One thing I did find cool with this sounding was the SARS having both the 7pm OUN 1999/5/3 sounding, and ICT 8pm 1999/5/3 sounding.Excellent length and curve to the hodograph until you get to that somewhat subtle backing so hopefully that wouldn't cause a significant issue in storm mode if something closer to the GFS verifies. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted April 23, 2016 Share Posted April 23, 2016 The 0z NAM increased shear over the dryline on Sunday, now 50-55kts. Clicking soundings and you're getting say a 77/64 environment at 0z that evening with CI occuring in a fairly nice environment favorable for a slow moving ESE big boy or two with increasing tornado potential as LCL's lower even more + the LLJ ramping up nicely after 0z. Doesn't scream something big but I love these nice little sleeper looking days from a chasing standpoint. I'd definitely be chasing if I lived in the area. Link to comment Share on other sites More sharing options...
Radtechwxman Posted April 23, 2016 Share Posted April 23, 2016 I know nam isn't in its good range yet but it goes out to 12z Tues. Has the trough at a neutral tilt and seems to have a euro'ish SFC low position. But only can take that with a grain of salt. If it waits to go negative tilt longer that could delay upper jet from reaching the best thermodynamics. Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 Sunday looking pretty decent if a supercell can initiate over north-central Oklahoma. Nice directional shear, leading to a nice'ish hodograph, and moderate instability. Even if a storm does form and does not produce a tornado, it would have pretty incredible structure. Link to comment Share on other sites More sharing options...
andyhb Posted April 23, 2016 Share Posted April 23, 2016 The 0z NAM increased shear over the dryline on Sunday, now 50-55kts. GFS getting up to near 50 kts. Good deep layer moisture and a lot of turning in the lowest 2 km. Fairly breakable cap from Central OK northward to the KS/OK border. Link to comment Share on other sites More sharing options...
bdgwx Posted April 23, 2016 Share Posted April 23, 2016 I am almost always a lurker but I wanted to comment about the false notion that there is a dramatic change once the trough comes ashore. It has been discussed many times in the Mid-Atlantic forum but to recap DTK's statement on this topic is that both the North and Southern Hemisphere have very similar model verification even though the southern hemisphere has less upper air samplings and observations in general. So I wouldn't expect a sudden increase in skill on Monday. Yeah, I've seen dtk mention that more than once. He also mentioned that the special soundings that were ordered in advance of the east coast blizzard had little if any significant impact on the forecast. I have to be honest, I can't remember the last time I've seen a material change in the location of the height and wind fields immediately after the upper air stations sampled a wave. I'm sure it's happened, but not frequently enough for me to notice anyway. There's just so many sources of data now including aircraft soundings which I've been reading are being equipped with instruments that are as good as or even superior to the RAOBs in many cases. Link to comment Share on other sites More sharing options...
andyhb Posted April 23, 2016 Share Posted April 23, 2016 Well, there's your poor run to run consistency for the GFS for Tuesday. Very high amplitude compared to basically everything else, although the triple point still looks quite favorable. Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 Well, there's your poor run to run consistency for the GFS for Tuesday. Very high amplitude compared to basically everything else, although the triple point still looks quite favorable. Deep-Layer Shear on the 00Z GFS is non-existent, or may as well not exist, being only ~30kts across the main threat area at 00Z. Link to comment Share on other sites More sharing options...
brettjrob Posted April 23, 2016 Share Posted April 23, 2016 Fully agree with OKpowdah, andy, and others regarding the overhyping of "wait for it to come onshore." With today's data assimilation systems, it isn't going to make a big difference. Watching the 00z GFS come in for Tuesday - my biggest concern remains the increasingly meridional nature of the upper flow on the east side of the low. The two main issues this presents are (1) VBV, and/or (2) the possibility that storm-relative flow in the upper levels is quite weak. But no setup is going to look perfect from 96 hours out. Now that the consensus seems to be shifting away from the progressive idea of ejecting the wave way early in the day, this is still the most ominous I-35 event modeled at this stage since 14 April 2012. I'd say the caveats for Tuesday don't look any worse right now than they did four days before that. Link to comment Share on other sites More sharing options...
andyhb Posted April 23, 2016 Share Posted April 23, 2016 Meanwhile the GFS goes and tries to show perhaps the best W KS setup since 2008 on Friday. Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 Meanwhile the GFS goes and tries to show perhaps the best W KS setup since 2008 on Friday. No joke... Sounding is from around DDC at 7pm on Friday. Saturday also continuing to look impressive. Link to comment Share on other sites More sharing options...
brettjrob Posted April 23, 2016 Share Posted April 23, 2016 Deep-Layer Shear on the 00Z GFS is non-existent, or may as well not exist, being only ~30kts across the main threat area at 00Z. The GFS is probably underestimating the backing of surface winds, which would have a significant impact in this regard. With 40-60 kt flow at H5 overspreading the dryline and adjacent warm sector as depicted on this run, I strongly doubt bulk shear would be 30 kt. Even so, the kinematic profiles above H5 on this run are certainly less than ideal for an historic outbreak. Link to comment Share on other sites More sharing options...
bdgwx Posted April 23, 2016 Share Posted April 23, 2016 It looks like the mid level jet streak might be better positioned across the warm sector on Wednesday. I can find some interesting soundings for Wednesday as well...at least according to the 0Z GFS. Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 Fully agree with OKpowdah, andy, and others regarding the overhyping of "wait for it to come onshore." With today's data assimilation systems, it isn't going to make a big difference. Watching the 00z GFS come in for Tuesday - my biggest concern remains the increasingly meridional nature of the upper flow on the east side of the low. The two main issues this presents are (1) VBV, and/or (2) the possibility that storm-relative flow in the upper levels is quite weak. But no setup is going to look perfect from 96 hours out. Now that the consensus seems to be shifting away from the progressive idea of ejecting the wave way early in the day, this is still the most ominous I-35 event modeled at this stage since 14 April 2012. I'd say the caveats for Tuesday don't look any worse right now than they did four days before that. Personally I do not remember there being very many problems whatsoever with 4/14/12 four days in advance, even looking back at the thread, nobody seemed to see any potential issues with anything relating to the setup. Then it went on the next day to be a D3 MDT. Link to comment Share on other sites More sharing options...
andyhb Posted April 23, 2016 Share Posted April 23, 2016 The GFS is probably underestimating the backing of surface winds, which would have a significant impact in this regard. With 40-60 kt flow at H5 overspreading the dryline and adjacent warm sector as depicted on this run, I strongly doubt bulk shear would be 30 kt. Even so, the kinematic profiles above H5 on this run are certainly less than ideal for an historic outbreak. I have to wonder if it is mixing the dryline too far E (as it very, very often does) on Tuesday. That would mean you might still get better mid/upper level winds overlapping it on Tuesday if it was closer to the TX/OK border. That's also partly a symptom of it not seeing the ageostrophic/isallobaric low level response very well. Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 https://twitter.com/ericfisher/status/723640873846726656 Man the Euro has really been pummeling the GFS lately as far as performance goes, so maybe we shouldn't be so concerned about what the GFS is showing, essentially like Andy and quite a few others have been saying. Link to comment Share on other sites More sharing options...
SnowWeenie Posted April 23, 2016 Share Posted April 23, 2016 Yeah, I've seen dtk mention that more than once. He also mentioned that the special soundings that were ordered in advance of the east coast blizzard had little if any significant impact on the forecast. I have to be honest, I can't remember the last time I've seen a material change in the location of the height and wind fields immediately after the upper air stations sampled a wave. I'm sure it's happened, but not frequently enough for me to notice anyway. There's just so many sources of data now including aircraft soundings which I've been reading are being equipped with instruments that are as good as or even superior to the RAOBs in many cases. Yeah I cant remember either it probably does happen but for synoptic scale features its more subtle like a small change in the tilt of the trough rather than a dramatic shift from the run before its better sampled to the after like a lot of people expect. I feel like this idea that extra soundings or sampling will drastically increase model skill comes from the past when less data was assimilated and adding a few extra RAOBs did actually increase skill. As you said there is so much data from many different sources especially aircraft and satellites its hard to get dramatic changes that aren't in the long range which is good. Model verification at medium range is really amazing and really shows how much NWP has improved over the last decade. Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 ..THERE IS A SLGT RISK OF SVR TSTMS FROM WESTERN IA PARTS OF EASTERN NEB AND NORTHWEST MO THROUGH EASTERN KS TO NORTH-CENTRAL OK... ...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT RISK AREA FROM EASTERN SD AND SOUTHERN MN INTO A SMALL PART OF ADJACENT WI TO WESTERN AND CENTRAL OK... ..SUMMARY STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE SUNDAY AFTERNOON AND EVENING ACROSS PARTS OF OKLAHOMA AND EASTERN KANSAS INTO THE MIDDLE MISSOURI VALLEY TO SOUTHERN MINNESOTA. ..SYNOPSIS A MID- TO UPPER-LEVEL TROUGH...CURRENTLY MOVING INTO THE WESTERN STATES PER WATER-VAPOR IMAGERY...IS EXPECTED TO REACH THE HIGH PLAINS FROM EASTERN WY TO EASTERN NM BY 12Z SUNDAY. A CLOSED LOW AT THE NORTHERN PORTION OF THIS TROUGH WILL MOVE SLOWLY TO THE EAST FROM WY INTO SD/NEB...WHILE THE SOUTHWARD-EXTENDING SHORTWAVE TROUGH LOSES AMPLITUDE TRACKING ACROSS THE CENTRAL PLAINS TO THE MID MS VALLEY. A COMPACT CLOSED LOW/SHORTWAVE TROUGH MOVING ACROSS SOUTHERN BAJA FRIDAY EVENING IS EXPECTED TO PROGRESS EASTWARD THROUGH SOUTH TX SUNDAY MORNING AND THEN ACROSS THE NORTHWEST GULF OF MEXICO. MEANWHILE...THE NEXT UPSTREAM PACIFIC TROUGH WILL MOVE INLAND AND AMPLIFY ACROSS THE WESTERN STATES SUNDAY AND SUNDAY NIGHT. AT THE SURFACE...AN AREA OF LOW PRESSURE ATTENDANT TO THE WY CLOSED LOW WILL GRADUALLY WEAKEN AS IT TRACKS ACROSS SD INTO SOUTHWEST MN BY 12Z MONDAY ALONG A QUASISTATIONARY BOUNDARY. MODELS DIFFER SOME WITH THE PLACEMENT OF THIS BOUNDARY...THOUGH GENERAL AGREEMENT SUGGESTS IT SHOULD EXTEND FROM EAST-CENTRAL SD THROUGH SOUTHERN MN TO CENTRAL WI AND CENTRAL LOWER MI. IN ADDITION TO THE LIKELIHOOD FOR CONVECTIVE DEVELOPMENT IN VICINITY OF THE AFOREMENTIONED WEST-EAST ORIENTED BOUNDARY...STRONG TO SEVERE STORMS WILL BE MORE LIKELY ALONG AND EAST OF A DRY LINE EXTENDING SOUTHWARD THROUGH EASTERN NEB...CENTRAL KS TO WRN OK/TX PANHANDLE BORDER TO TX BIG BEND BY MID AFTERNOON SUNDAY. ...PORTIONS OF SOUTHERN/CENTRAL PLAINS TO MID MO VALLEY AND SOUTHERN MN... THE PRESENCE OF LOW-LEVEL OFFSHORE FLOW INTO THE GULF OF MEXICO AS A LARGE AREA OF HIGH PRESSURE ADVANCES ACROSS THE EASTERN U.S. TODAY INTO SUNDAY WILL RESULT IN A RELATIVELY NARROW PLUME OF MOISTURE RETURN ACROSS THE WARM SECTOR ON SUNDAY. SOUTHERLY LOW-LEVEL WINDS LOCATED EAST OF THE DRY LINE WILL TRANSPORT SURFACE DEW POINTS IN THE MID-UPPER 50S INTO PARTS OF SOUTHERN MN AND SOUTHWEST WI...WHILE VALUES NEAR 60 F SHOULD EXTEND INTO WESTERN/CENTRAL OK BY LATE SUNDAY AFTERNOON. STEEP MIDLEVEL LAPSE RATES EXPECTED TO BE ALREADY PRESENT ACROSS THE CATEGORY 1 AND 2 SEVERE RISK AREAS AT 12Z SUNDAY COMBINED WITH THE POLEWARD MOISTENING AND SURFACE HEATING WILL RESULT IN MODERATE INSTABILITY. SHOWERS AND THUNDERSTORMS SHOULD BE ONGOING AT 12Z SUNDAY NEAR AND NORTH OF THE SURFACE LOW AND QUASISTATIONARY BOUNDARY...WITHIN STRONG LOW-LEVEL WARM ADVECTION AND WEAK HEIGHT FALLS AHEAD OF THE HIGH PLAINS TROUGH. CLOUDINESS ATTENDANT TO THIS ACTIVITY MAY LIMIT DESTABILIZATION WITH NORTHWARD EXTENT ACROSS EASTERN SD TO WEST-CENTRAL/SOUTHWEST WI...WITH A LOWER PROBABILITY FOR STRONG TO SEVERE STORMS SUNDAY AFTERNOON AND EVENING. A GREATER LIKELIHOOD FOR STRONG TO SEVERE STORMS WILL BE FOUND ACROSS THE SLIGHT RISK AREA...WHERE MODERATE INSTABILITY COMBINED WITH VERTICALLY VEERING WINDS /INCLUDING 50-60-KT SOUTHWESTERLY 500-MB WINDS/ WILL RESULT IN STRONG TO SEVERE STORM DEVELOPMENT SUNDAY AFTERNOON. EFFECTIVE BULK SHEAR OF 35-45 KT WITH AN ORTHOGONAL ORIENTATION TO THE DRY LINE SUGGESTS DISCRETE SUPERCELLS CAN BE EXPECTED WITH ALL SEVERE HAZARDS. WEAKER TO NEUTRAL HEIGHT FALLS INTO OK MAY TEND TO LIMIT THE COVERAGE OF STORMS. Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 12Z NAM likes the Triple point and warm front at 84 hours for having the best environment. Link to comment Share on other sites More sharing options...
OUGrad05 Posted April 23, 2016 Share Posted April 23, 2016 12Z NAM coming in now, at 7pm LI's just to the west of I35 corridor are -10 to -14. There are still some differences between upper air features and surface features that are a bit concerning. Triple point is looking pretty potent up in central KS as well. Link to comment Share on other sites More sharing options...
JasonOH Posted April 23, 2016 Share Posted April 23, 2016 500mb trough still lags a bit before ejecting. If this speeds up, the dryline will also be a good play Link to comment Share on other sites More sharing options...
jojo762 Posted April 23, 2016 Share Posted April 23, 2016 NAM would keep highest tornado threat over the triple point, SC/C KS, and C OK along the dryline. Trough is a bit slow still. Link to comment Share on other sites More sharing options...
Chicago Storm Posted April 23, 2016 Author Share Posted April 23, 2016 NAM with 5k CAPE. Probably overdoing CAPE a bit though, with pockets of 70+ DP's. Sharp DL though, which I like. Link to comment Share on other sites More sharing options...
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